Broken Add-on (only for one person though?)
Here is the error message followed by the section of code around line 2935:

Traceback (most recent call last):
  File "C:\Users\ryanl\AppData\Roaming\Blender Foundation\Blender\2.80\scripts\addons\Darkfall VFX Nodes1_2.py", line 2935, in draw
    icon="TRIA_DOWN" if obj.expanded else "TRIA_RIGHT",
AttributeError: 'NoneType' object has no attribute 'expanded'


def draw(self, context):
        layout = self.layout
        obj = context.object

        box = layout.box()

        row = box.row()
        row.prop(obj, "expanded", # Line 2935
            icon="TRIA_DOWN" if obj.expanded else "TRIA_RIGHT",
            icon_only=True, emboss=False)


It is possible that the user has put Blender into a state where context.object could be None by having no selected objects. For example, if a user deletes the selected object, there will be no selected object. It could also be that this is a side effect from another addon (one that deselects all objects, for example).

I am able to reproduce this error by starting with a new .blend file and deleting the default cube. I am also able to reproduce the error by running the following script in the text editor:

import bpy
bpy.context.view_layer.objects.active = None


You may want to handle the case where context.object is None. One way to handle this is by adding the poll class method to the panel. The draw method will only run if the poll method returns True.

    @classmethod
    def poll(cls, context):
        return context.object is not None




EDIT: I took a closer look at your script. The only reason an object needs to be selected is because the expanded property is stored inside of an Object. The object is not used elsewhere in drawing. I would consider a small redesign so that the property is stored somewhere else so that it is not necessary for the user to have an object selected. An example could be to store the property in the Scene object. Here is an example for how this could be done:

class Sub1Panel(bpy.types.Panel):
    """Creates a Panel in the Object properties window"""
    bl_label = "clonepanel"
    bl_idname = "OBJECT_PT_clone"
    bl_space_type = 'NODE_EDITOR'
    bl_label = "Clone Node"
    bl_region_type = "UI"
    bl_category = "Darkfall VFX Nodes"
    bl_options = {'DEFAULT_CLOSED'}
    bl_parent_id = 'OBJECT_PT_toolseffect'

    def draw(self, context):
        scene = context.scene

        box = layout.box()
        row = box.row()
        row.prop(scene, "Sub11Panel_expanded ",
            icon="TRIA_DOWN" if scene.Sub11Panel_expanded else "TRIA_RIGHT",
            icon_only=True, emboss=False    
        )

        if scene.Sub11Panel_expanded:
            row.label("label")


def register():
    bpy.utils.register_class(Sub11Panel)
    bpy.types.Scene.Sub11Panel_expanded = bpy.props.BoolProperty(default=False)

def unregister():
    bpy.utils.unregister_class(Sub11Panel)
    del bpy.types.Scene.Sub11Panel_expanded